Powering high and low voltage peripherals with one power supply

[kocokm]

Hello glorious reader. I am using an Arduino mega to control a 12v motor as well as other peripherals such as led's, LCD and some buttons. I want to use one power supply. 12v straight to the motor and use a buck converter to give 5V to the mega. My question is can I power the low voltage peripherals off the mega or is there a current issue even if I use a step down buck converter between the mega and 12v power supply?

[TomGeorge]

Hi, @kocokm
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@kocokm

My question is can I power the low voltage peripherals off the mega or is there a current issue even if I use a step down buck converter between the mega and 12v power supply?

You power all the 5V peripherals off the BUCK CONVERTER, not the MEGA and power the Mega of the BUCK CONVERTER.

Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.

This will help us understand your project.

Thanks.. Tom..

[gilshultz]

Welcome! If it were me I would use the buck converter and set its output to abut 8V and use it to feed Vin of the Mega, you will get some additional filtering. The low voltage peripherals, LCD and buttons should not draw over a few mills. Be sure to use a proper driver for the motor or a MOSFET, do not connect it directly to the Arduino. Post that schematic so we can be sure.

[kocokm]

Thanks tom idk why id did not think to do this myself. I also need to amplify digital signals from the arduino. I was thinking to do this with an NPN transistor.

[kocokm]

Yes thank you. I am now trying to think of a correct transistor setup to drive the motor.

[gilshultz]

@kocokm

I am now trying to think of a correct transistor setup to drive the motor.

Look at MOSFETs, they are inexpensive and will not burn as much power in heat when properly sized.

The 10K is to guarantee it is off during reset. The 150 resistor is to limit the inrush to your processor as the gate is capacitive. The diode is optional as many of the newer MOSFETs have an avalanche rating that will adsorb the flyback current.

[kocokm]

I need to give 4 control signals to use the motor that require 16V. The signals are digital waveforms and so is a npn inverter or a mosfet amplification better for this?

[kocokm]

would this work as a transistor setup, I calculated the 10k resistor from the current requirements of the port that the transistors attatch to which are the motor control signals

[jim-p]

@kocokm

would this work as a transistor setup,

No. When the transistors are ON you are just shorting 5V to ground.
Do you have a data sheet fot this motor that requires 16V control signals?

[kocokm]

yes the control signals output need 8V. The current of the output should be between 0.01 and 0.02 amps. Should I remove the 20k resistors? I thought they were pull down resistors to remove floating points.

[jim-p]

@kocokm

yes the control signals output need 8V.

Then you will need an 8V power source.

Should I remove the 20k resistors?

No

If you post the datasheet we can provide the proper interface circuit.